Beat rate indicator for musical instrument tuners



July 1, 1958 A. w. DICKEY ,8 1,

BEAT RATE INDICATOR FOR MUSICAL INSTRUMENT TUNERS Filed April 15, 1957 4 Sheets-Sheet 1 ALBERT W. DlCKE'Y W 6. H g

A. W. DlC KEY BEAT RATE INDICATOR FOR MUSICAL INSTRUMENT TUNERS Filed April 15, 1957 4 Sheets-Sheet 2 ALBERT W- D\CK EY July 1, 1958 A. w. DICKEY 2,341,045

BEAT RATE INDICATOR FOR MUSICAL INSTRUMENT TUNERS Filed April 15, 1957 4 Sheets-Sheet 3 l [IIIIIIlIIIIIIIIIIIIII/IIIIIIIIIIIIIII ALBERT W.D\CKEY July 1, 1958 A. w. .DICKEY 2,841,045

BEAT RATE INDICATOR FOR MUSICAL INSTRUMENT TUNERS Filed April 15, 1957 4 Sheets-Sheet 4 ALBERT w. DICKEY M 6. wk Z% United States BEAT RATE INDICATOR FOR MUSICAL INSTRUMENT T UNERS The invention relates to devices to aid in the tuning of musical instruments such as pianos, harps, harpsichords, pipe organs, and certain kinds of electric organs.

Prior to my present invention, other persons have invented stroboscopic tuning aids designed to give a visual indication when the sound frequency of the note to be tuned matches that of the stroboscope, but these prior art devices have inherent disadvantages which are prohibitive insofar as most itinerant professional instrument tuners and individual players who would like to tune their own instruments are concerned. They include complicated electronic circuits and associated mechanisms and in consequence thereof are not only very expensive to own but are so bulky and heavy as to be non-portable in most instances. Moreover, the fact that they all provide but one reference frequency for each of the notes in the chromatic scale is an undesirable limitation.

With the above-mentioned and other incidental disadvantages of stroboscopic tuning aids in mind, it is my primary object to provide musical instrument tuners of any class with an extremely simple, pocket-size tuning aid that actually weighs less than one pound, that can be pro duced at very low cost, and which has no delicate electronic components to get out of order and thus require expensive maintenance.

To be more explicit, my improved tuning aid is based upon the phenomenon of audible beat rates which occur when pairs of tones are sounded together in fifths and fourths. Its physical embodiment is a beat rate'indienter that can be utilized as a visual standard of reference for the several beat rates employed in tuning.

In departing from employment of complicated, expensive electronic circuits, an important object of my inventionis to insure that the only electrical components of the improved instrument are a timer motor of the type used in electric clocks and a simple electric flashlight.

()tber objects, advantages and features of the invention will become apparent as the following specific description is read in connection with the accompanying drawings, in which:

Fig. l is a fragmentary, partially exploded, and somewhat schematic perspective view of the instrument; Fig. 2 is a front elevation; Fig. 3 is a horizontal axial sectional view; Fig. 4 is a transverse vertical section on line 4-4 of Fig. 3; and Fig. 5 is a vertical axial section on line 55 of Fig. 4.

Fig. 6 is an enlarged, fragmentary, axial sectional view of the adjusting knob assembly.

Fig. 7 is a detail front elevation of the timing disk; and

Fig. 8 is a similar view of the note selector shield.

As explained in various published books and manuals onthe theory and practice of tuning, the equal-tempered (evenly divided) twelve-note chromatic scale can be produced by properly adjusting the audible beat rates which occur when pairs of tones are sounded together in fifths and fourths. The so-cal-led beats are the slight variations in sound level percieved by the ear and created by atent O the near unison harmonics of the basic tones. For example, if the note A has a frequency of 220 cycles per second, its third harmonic is 660 cycles, which is near the 659.25 cycles of the fourth harmonic of the note E, a tempered fourth below A. The note E is correctly tuned when its fourth harmonic is flat with respect to the third harmonic of A by .75 cycle per second. In other words, the beat must be .75 per second, or per minute. Likewise, the beat of B with B should be 33.5 per minute. The beat rates for the complete range of note comparison appear in the following table.

E with A should be 45 per min.

B with B should be 33.5 per min. Ft with B should be per min. Cii with Ft should be 37.5 per min. Gt with Cit should be 5 6 per min. Dii with Git should be 42 per min. Ait with Di should be 63 per min. F with Ali should be 47 per min. C with F should be 35.5 per min. G with C should be 5 3 per min.

D with G should be 40 per min.

The above figures exist only in a mathematically perfect equal-tempered chromatic scale where each tone ascending is 1.05946 times the frequency of the tone below it. Professional tuners generally do not attain such perfection, but they all depend upon some sense of the different beat rates required to establish the basic scale. They rarely use a standard of reference because, prior to my present invention, no convenient and practical means toward that end has existed that is applicable for the rapidly decaying tones of the piano. Instead, they rely principally upon the knowledge that E tunes a little flat with A, whereas Aii tunes a little more fiat with Dii, et cetera. As a consequence, their work varies considerably, depending upon their mood and luck in any given instance. My invention will enable the professionals and the non-professionals as well to do a truly scientific job of establishing the scale, or, in the jargon of the trade, laying the bearings.

In the above table, a difierent beat rate is listed for each note. However, various authorities have pointed out that six different rates actually will suffice for establishing quite an acceptable scale. For instance, W. B. White, in his book Piano Tuning and Allied Arts published for the Tuners Supply Company, of Boston, recommends that beat rates of .6, .7, .8, .9, 1.0 and 1.1 per second be used. Translated into beats per minute, that means, respectively, 36, 42, 48, 54, and 66 per minute, and these are the reference rates that I have embodied in my invention. It will be obvious, once the principle of the invention is understood, that others could be provided if desired.

It is my observation that many professional pianists and a great many ordinary players would like to tune their own instruments, but cannot do so because they do not understand how to produce very necessary imperfections in the basic scale. The novice invariably tunes the fifths and fourths too perfectly, this being the natural and easy thing to do with a good musical car. My invention, therefore, is a tuning aid in the physical form of a beat rate indicator intended to show even the novice the exact amount of deviation from perfection that is required to produce the practical equal-tempered scale.

Specifically, my invention provides an accurate timer arranged to interrupt a light source at rates, selected at will, from .6 to 1.1 times per second in steps varying by .1 second. By watching the rate of blinking light flashes while simultaneously manipulating the tuning hammer, or

, cator includes a protective casing which may be of any desired form suitable to contain the operational parts with satisfactory economy of space.

Means is provided inside casing 10 to produce precisely timed light flashes at selected intervals that will be visible to an observer through a window 11 in front wall 12 of said casing. This meansincludes a source of light 13 which may be a standard inexpensive flashlight in the interest of economy. A light directing element 14 is mounted in a position to direct light rays from source 13 toward casing window 11 and is of special shape for a reason which will be explained fully hereinafter. An apertured timing element 15, which preferably is in the form of a rotatable disk, is mounted in interposed relation to light directing element 14 and easing window 11. Also, an apertured note selector shield 16 i is interposed between timing disk 15 and casing window 11 and is made rotatably adjustable preferably by being aflixed to a shaft 16' that is journaled in front casing wall 12 in coaxial relation to said timing disk. Means for rotating timing disk 15 at constant speed preferably is constituted by a prime mover 17, which may be an A. C. motor of the type used in electric clocks. For the purposes of my invention, motor 17 must drive timing disk 15 at a speed of one revolution per minute. Suit able means, such as a finger knob 18, is provided on the exposed end of shaft 16' for use by an instrument tuner in selectively adjusting note selector shield 16 in anguelement 14, light rays from source 13 will be distributed through a diverging channel to each aperture 21 in any of the concentric rows as it moves through a position in registration with window 11 and will appear to the observer as a brilliant, colored flash.

Note selector shield 16 has one aperture 22 for each musical note to be struck in the tuning process. The relative arrangement of the several apertures 22 should be such that they will lie in different radial directions from the rotational axis of note selector shield 16. (Fig. 8). On the outer face of front wall 12 of casing 10, indicia 23 are inscribed to designate the respective notes of the scale to be tuned and are arranged in convenient order in the arc of a circle concentric to finger knob 18. Radial lines lead inward to knob 18 from the several indicia 23 so as to be traversed by an'index pointer 25 provided on said knob. The location of the respective indicia 23 is such that, when knob 18 is turned to bring index pointer 25 into registration with the line 24- of any selected note indicia 23, the aperture 22 in shield 16 corresponding to that particular note will come into registration with window slot 11.

The respective apertures 22 in shield 16 are also arranged at such radial distances from the rotational axis that each one will register with the circumferential row of apertures 21 in timing disk 15 that determi es the best rate of light flashes to be utilized in tuning the corresponding musical note. Consequently, when knob 13 is set for a selected note to be tuned, successive light flashes from source 13 will penetrate the moving apertures 21 of the appropriate circumferential row in timing disk 15 and the aperture 22 of shield 16 that has been brought into stationary registration with window 11. The light flashes thus will occur intermittently at the proper 7 beat rate for the selected note.

lar rotation about its axis. Knob 18 may be removably secured to shaft 16 by suitable means such as setscrew 16". Motor 17 may be plugged into a wall outlet of electric power conveniently by means of cord 19.

Timing disk 15 preferably is afiixed to a driven shaft 20 that is operatively connected to motor 17 by speedreduction gearing 17 of a ratio designed to drive said shaft at a speed of one revolution per minute.

In accordance with my invention, timing disk 15 is provided with six circular rows of signal producing means constituted by apertures 21 arranged concentric to the rotational axis of said disk in cooperation with light projecting means 13--14. (Fig. 7). Each aperture 21 should be approximately onesixteenth of an inch in diameter and may be either an actual hole or a transparent or translucent insert in an opaque disk, which latter may be of metallic or plastic composition. The apertures 21 of each circular row are evenly spaced and those of the outermost row are sixty-six in number. In the other rows, the number of apertures 21 in succession from outside to inside are respectively sixty, fifty-four, fortyeight, forty-two and thirty-six.

It will be observed that window 11 in front wall 12 of casing 10 is in the form of a straight slot arranged radially in relation to the common rotational axis of tim- Fig. 3 in particular shows motor 17, flashlight 13 and light directing element'14 in their actual space relationship. Element '14 is bent so as to direct the light rays first obliquely and then axially forward in order that the flashlight may be located alongside motor 17 in aposttion to effect compactness and permit ease of replacement.

The several parts of the internal mechanism are mounted on suitably shaped brackets and other supports, the exact details of which are not essential to the present disclosure.

The function of note selector shield 16 will be understood more fully from the following examples. When the index pointer 25 on knob 18 is set at D# (one of the twelve tones marked on casing 10 by indicia 23), a single aperture 22 in note selector shield 16 will be in registration with window'slot 11 and at the exact radial distance 'from the common rotational axis of said shield and timing disk 15 to match any registering aperture 21 in the 42-aperture row in said disk. An observer then will see only the .7 per second flash rate produced by the 42- aperture row of timing disk 15. This is the proper beat rate for tuning D# with G#. If knob 18 then is turned to A#, another aperture 22 of note selector shield 16 will move into view through the window slot 11 in match- 7 ing relation to the outermost row of apertures 21 in timing disk 15 and note selector shield 16 and that it spans all six rows of apertures 21 in disk 15 in a vertical plane. In conformity with this window slot arrangement, light directing element 14 is in the form of a fiat plate of a substance possessin the peculiar light channeling properties of Plexiglas or Lucite. This plate may be colored red to make the light flashes readily distinguishable, and is 'preferably fan-shaped and arranged with its narrow base edge closely adjacent to light source 13 and its wide opposite edge in the plane of window slot 11 and closely adjacent to the inner face of timing disk 15. Due to this arrangement of light directing ing disk 15 and a flash rate of 66 per minute will be observed, or 1.1 per second. This is the proper beat rate for tuning A# with D#.

In the use of the beat rate indicator, it is set at some convenient place near the instrument to be tuned and connected by cord 19 to an A. C. power outlet. If, by way of example, a piano is to be tuned, the procedure is as follows. The usual strip of felt employed by tuners is placed between the strings in the octave from E to E (counting from left to right on the keyboard) so that only the center string of each note can vibrate. The note A (Cello A) is first tuned to any desired pitch (usually 2 20 vibrations per second) with an ordinary hand tuning form, or other musical instrument, as a reference. The accuracy of the beat rate indicator is independent of the pitch of this first, or key note.

It is of course best to do the tuning in quiet surroundings. At best, the 'beats are of low intensity relative to the primary sound from the strings and can be heard for only a few seconds after striking a pair of notes. Even though the time is short, it is suflicient for the tuner to make a comparison with the blinking rate of the indicator and do some adjusting. Usually three or four strikes are sufficient.

With the knob of the indicator set at E, tune E so that the audible beat heard when A and E are struck simultaneously is .7 per second, flat. That is, adjust E so that it is just slightly lower in pitch than it would be if no beats were audible. The .7 per second beat rate is arrived at when it sounds in time" with the red light flashes observed.

The knob is then set at B. This is B The required beat rate is .6 per second, flat with respect to B Tune B accordingly, using the flash rate of the indicator as a reference. In like manner set knob at F# (i. e. F# and tune F# fiat by .8 beat per second with respect to B Proceed similarly to tune in succession C# Git-' Dil A# F 40, G and D in each instance adjusting the particular note so that the beat rate with respect to hte preceding note in this series is flat by the amount shown by the rate indicator.

If now the note D is sounded with A (the note on which the scale was 'based) the beat rate should be .968 per second, and above unison, or sharp. This step proves the accuracy of the previous procedure for all 12 notes. It, in adjusting D so that the beat with respect to G is .7 per second fiat, that same adjustment produces a beat of nearly 1 per second sharp with respect to A then, since the pitch of G depended on the pitch ofeach of the notes before it, the whole scale must be accurate.

The above described procedure results in a set of conditions that can be tabulated as follows:

Note Frequency Harmonies Beats Beats Steps Being of Note, causing per per Tuned cycles per beats sec. min.

sec. flat flat Tune An to desired Pitch A" 220 assumed 3rd, 4th 7 42 Tune with Ai1... E sm,2h i c as with El! B. $12 322 3rd, 4th 8 48 with B" Fa. $32 88? 3rd, 2nd 6 36 with Fa. 01th ,ggfgg 3r 4th 9 54 with on. Gian ,ggg; 3rd, 2nd 7 is with on. Dita 3rd, 4th 1 l as with on, An. ,ggg; 3rd, 4th 8 48 W1thA#zs F3! ,Ei 3rd, 2nd 6 as with F" C40 3rd, 4th 0 54 with oh Gas 3rd, 2nd 7 42 with G1: Di, ,ggg: 3rd, 4th 1 0 so check With D4: A" 220. 000

1 The theoretically exact frequency of the note. The figure directly above each of these is the actual frequency existing it the beat rate shown in column 5 prevails.

It will be noted that the same beat rate is present for several difit'erent notes. B, C#, and C are all adjusted to give .6 beat per second for example. By use of this invention the tuner need not know what the figure is, nor which note requires which rate; he simply sets the index at the note to be tuned and observes the rate directly.

As was stated previously, this invention is based on the premise that beat rates of .6, .7, .8 per second, etc., are sufiiciently accurate for establishing the equal-tempered chromatic scale. The proof of this can be seen in the following example. In the table above, the note that is the most inaccurate when compared to a mathematically perfect one is D#; it is .04 cycle/sec. too sharp. This, however, the greatest error in the whole scale, amounts to only a little more than 0.01%. Considering that some notes in the chromatic scale are as much as 1% in error relative to the musically perfect diatonic scale, such discrepancies are insignificant. It is, of course, possible to make the rate indicator more accurate by putting more rows of apertures on the disk and a greater variety in number of apertures per row, but this seems needless.

it is of interest to consider how much error occurs if the commercial power which drives the timing motor is off frequency by some uncommondy great amount. Suppose it is 59 instead of the usual 60 cycles. That is 1.57% slow (or 24 minutes per day), and the flashes of light from each of the rows of apertures would therefore be 1.67% slower. Therow that normally gave .7 flash per second would then be reduced to .69, but this figure is still quite sufficiently accurate for tuning. However, an error of this magnitude in direct comparison stroboscopic devices could not be tolerated.

Having established the basic scale in the manner described, the felt damping strip is removed and the tuning proceeds in all other respects according to accepted practice.

It will be apparent to anyone familiar with the tuning art that a beat rate indicator of the kind described herein would be applicable in the tuning of the other musical instruments mentioned in the preamble. It is common practice in setting the base scale of instruments that produce sustained tonessuch as an organ-to count the beats per minute, using an ordinary Watch for a time piece. This is a slow trial and error process although quite accurate. With the beat rate indicator, the tuning adjustment, whether it be by a wrench, or a slider along a pipe, or other means, is done more or less continuously until the audible beats are in time with the flash rate of the red light, a straight forward, uncommonly accurate, and quick process.

it will be understood that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purpose of illustration which do not constitute departures from the spirit of the invention and scope of the appended claims.

I claim:

1. A heat rate indicator for musical instrument tuners comprising: an opaque casing having a light-penetrable window in the formof a straight slot; a timing element movably mounted inside said casing directly opposite to said window and having at least one row of equally spaced signal producing means arranged in transverse relation to said window to be viewed therethrough from the outside; means to move said timing element at constant speed in a manner that causes successive signal producing means in the row to pass the casing window at time intervals corresponding to the beat rates required in tuning a harmoniously related pair of notes of the equal-tempered chromatic musical scale; and a movable opaque note selector shield interposed between the timing element and the casing window and being provided with at least one note-representing aperture located directly opposite to .the row of signal-producing means of the timing element, said note selector shield being movable in the same direction as the timing element to permit the aperture of said shield to be moved into registration with the casing window so that passage of each signal producing means may be viewed through said aperture and window.

2. A beat rate indicator for musical instrument tuners as defined in claim 1, wherein there are plural substantially parallel rows of signal producing means carried by the timing element with the spacing between rows and the spacing of signal producing means in the respective rows being such that the respective frequencies of passage of the signal producing means by the casing window will correspond to the beatrate of other harmoniously related notes of the scale; and wherein the note selector shield has plural apertures Corresponding to the respective notes of the scale to be tuned and respectively arranged window-slotwise to register with the corresponding row of signal producing means of the timing element, said apertures also being arranged in staggered relation lengthwise of said rows of signal producing means in a manner whereby only one selected aperture may be brought into registration with the casing window by appropriate adjustment of the movable selector shield.

3. A beat rate indicator for musical instrument tuners comprising: an opaque casing having a light-penetratable window; a light source located inside said casing; means to direct light rays from said source toward said casing window; light flash timing means including a rotatable disk located in interposed relation to said light source and said casing window and having at least one circular row of uniformly spaced apertures arranged concentrically to the rotational axis thereof; means to rotate said timing disk at a constant speed that causes successive apertures in the row to pass the casing window at time intervals corresponding to the beat rates required in tuning a harmoniously related pair of notes of the equaltempered chromatic musical scale, a note selector shield interposed between the timing disk and the casing window and being rotatable about the axis of said timing disk, said note selector-shield being provided with at least one note-representing aperture located at the same radial distance from the common rotational axis as the row of apertures in the timing disk and adapted to be brought into registration with the casing window to permit light rays to be projected through said window as each aperture of the timing disk successively passes the exposed aperture of the note selector shield; and means by which said note selector shield may be adjusted angularly about its axis.

4. A beat rate indicator for musical instrument tuners as defined in claim 3, wherein .there are plural concentric rows of apertures in the timing :disk withthe radial spacing between rows and circumferential spacing between apertures in the respective rowsibeing such that the re-i spective frequencies of passage of the apertures therein by the casing window will correspond to the beat rate of other harmoniously related notes of the scale; wherein the casing window is in the form of a straight slot arranged radial to the common rotational axis of the timing disk and note selector shield; and wherein the note selector shield has plural apertures corresponding to the respective notes of the-scale to be tuned and respectively' arranged angularly with respect to said rotati nal axis and in radial distance therefrom in a' manner reby each shield aperture will correspond to a difiercnt note to be tuned and be located in registration with the appropriate row of timing disk apertures; an index pointer provided on the means by which the note selector shield may be adjusted angularly and note indicia arranged on the casing in appropriate relation to the respective shield apertures to cause any selected note aperture to be brought into registration with the casing window. 7

5. A heat rate indicator for musical instrument tuners as defined in claim 4, wherein the light directing means is in the form of an axially tapered plate of material possessing the light channeling properties of Lucite and is arranged with its inner edge closely adjacent to the light source and its opposite edge substantially in the plane of the casing window and closely adjacent to the inner face of the timing disk.

References Cited in the file of this patent I UNITED STATES PATENTS r 1,889,128 McClintock, 11'. Nov. 2.9,T932 

